Microhardness of dual-polymerized resin cement around a translucent fiber post in the intraradicular environment

Abstract

Aim:In this study, we evaluated the effect of photopolymerization on Vickers microhardness of dual-polymerized resin cement at three locations when a translucent quartz fiber post was used.Materials and Methods:Single-rooted bovine teeth received quartz fiber post systems (length: 12 mm) using a dual-polymerized resin cement. In Group 1, the posts were cemented but not photopolymerized, and in Group 2, the posts were both cemented and photopolymerized. After cementation, approximately 1.5-mm thick sections were obtained (two cervical, two middle, and two apical) for regional microhardness evaluations.Statistical Analysis:Statistical analyses were performed using the SPSS software (ver. 11.0 for Windows; SPSS, Inc., Chicago, IL, USA). Microhardness (kg/mm2) data were submitted to two-way analysis of variance (two-way ANOVA) and repeated measures with microhardness values as the dependent variable and polymerization status (two levels: with and without) and root region (three levels: cervical, middle, and apical) as independent variables. Multiple comparisons were made using Dunnett's T3 post-hoc test. P values of <0.05 were considered to indicate statistical significance in all tests.Results:Photopolymerization did not significantly change the microhardness values when compared with no photopolymerization. Microhardness values also showed no significant difference between the three regions in the root canals in both groups.Conclusions:The mode of polymerization of the cement tested in combination with the translucent quartz fiber post system did not affect the microhardness of the cement at the cervical, middle, or apical regions of the root.

Degree of conversion of resin composite cured by light through a translucent fiber posts

“…The degree of conversion was decreased when the depth and distance apart from the post surface increase and drastically decrease when the depth from the top of the post was greater than 6 mm. This data conformed to several studies that the light transmitted through the post was drastically decreased when the depth from the top of the post more than 4-6 mm13,14,15,16 and showed insufficient transmission of light to polymerize the resin cement or composite 15,16. This means that in clinical situation, the expectation of light-cured mode of resin cement cannot be expected especially in deeper part more than 4-6 mm and also the area apart from the post.…”

“…All studies concluded that the quantity of light transmitted depends on the resin matrix and the fiber composition of each post. However, most studies recommend using FTIR methodology to directly evaluate the degree of conversion on the cement 12,13,14,15,16. Faria e Silva et al17 employed the Fourier Transform Raman (FT-Raman) spectrometer which is a more accurate method to evaluate the degree of conversion for resin cement cured through the post.…”

Degree of conversion and adhesion of methacrylate-based resin cements with phosphonic or phosphoric acid acrylate to glass fiber posts at different regions of intraradicular dentin

“…The employment of translucent posts help to improve the light transmission from the polymerization device through the post and increase stiffness of the photo-polymerized part of the resin cements in the root canal [1,17]. The results of this study support this statement at least for the tested FRC post in that DC did not significantly change from coronal to apical parts of the root.…”

Influence of curing protocols on water sorption and solubility of a self-adhesive resin-cement

“…Most studies do not use any device for stability, with constant support. Even though constant pressure during these periods was not employed by other authors [4][5][6]10,12,13,[22][23][24]29 , and it is not clinically appropriate, this parameter may have influenced the results, because any loss of stability may favour the formation of microvoids and consequently increase water sorption and solubility.…”

“…Dual-curing resin cements of different brands showed different behaviours as to the degree of conversion and mechanical properties when cured with different light-activation protocols [22][23][24] . While some cements are more suitable for situations where immediate light-activation is possible, others show a better behaviour when the light-activation is limited 23 .…”